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Income Taxes (Details) - USD ($)	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017	Dec. 31, 2017
Segment Reporting Information [Line Items]
Effective tax rate	21.60%	36.60%	23.30%	35.70%
U.S. federal corporate tax rate			21.00%		35.00%
Adjustment to provisional amount reducing income tax expense from continuing operations	$ 700,000
Unrecognized tax benefits	$ 1,800,000.0		$ 1,800,000.0
Impact of unrecognized tax benefits on tax liability			$ 1,400,000
United States
Segment Reporting Information [Line Items]
Open tax year	2013
United Kingdom
Segment Reporting Information [Line Items]
U.S. federal corporate tax rate			19.00%
Open tax year	2016
Brazil
Segment Reporting Information [Line Items]
Open tax year	2012

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Tax Cuts And Jobs Act, Measurement Period Adjustment, Income Tax Expense (Benefit)

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

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